s4-drs: Make drs_ObjectIdentifier_to_dn() safer and able to cope with DummyDN values
We want to totally ignore the string DN if there is a GUID,
as clients like "Microsoft Azure AD connect cloud sync" will
set a literal "DummyDN" string.
RN: Use of the Azure AD Connect cloud sync tool is now supported for
password hash synchronisation, allowing Samba AD Domains to synchronise
passwords with this popular cloud environment.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=10635
Signed-off-by: Andrew Bartlett <abartlet@samba.org>
Reviewed-by: Stefan Metzmacher <metze@samba.org>
(cherry picked from commit
73f3ece8b2b44ac4b3323a08fb969f29bf2b0380)